JPS6043173A - Engine controlled in number of operating cylinder - Google Patents

Abstract

PURPOSE:To restrict the change of torque by controlling an ignition timing before switching upon switching the number of operating cylinders. CONSTITUTION:When an operating condition, in which the number of operating cylinders should be switched, is detected, a switching signal (d) is outputted to an actuator 5 and, simultaneously, an ignition timing signal (c), in which the ignition timing is corrected comparing to the spark angle in the condition before switching, is outputted to an ignition coil 4. According to this method, the maximum pressure in the cylinder is reduced and a generating torque per one cylinder may be reduced, therefore, the stepwise sudden increase of the torque of whole of the engine may be restricted and a shock to the body of vehicle may be mitigated.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an improvement in a cylinder number controlled engine in which operation of some cylinders is suspended depending on engine operating conditions.

<Prior art> In general, fuel efficiency tends to be better when the engine is operated under heavy load, and for this reason, in a multi-cylinder engine, operation of some cylinders is stopped (hereinafter referred to as cylinder reduction) in an operating range where the total load is small. An oil/fuel ratio control engine has been proposed that improves fuel efficiency in the operating range by relatively increasing the load on the remaining active cylinders by this amount.

As this type of cylinder number control engine, for example,
There are those shown in Japanese Patent Application No. 0-28770 and Japanese Patent Application No. 123900-1983.

However, in conventional engines with controlled number of cylinders, immediately after switching the number of operating cylinders, the operating control conditions remain the same as before the switching, and only the number of operating cylinders changes, resulting in a sudden change in engine torque. This causes a large shock and discomfort to the passengers, and especially immediately after switching from reduced-cylinder operation to all-cylinder operation, torque increases rapidly, which places a heavy burden on the engine mount and drive system. This has caused a problem of reduced durability.

On the other hand, it is known that if the ignition timing is retarded from the point at which the maximum combustion pressure is obtained, the combustion pressure will decrease and the torque will decrease.

<Purpose of the Invention> The present invention has been made in view of the above points, and is intended to alleviate torque fluctuations by correcting and controlling the ignition timing immediately after switching the number of operating cylinders, thereby eliminating discomfort to the occupants. An object of the present invention is to provide an engine with a controlled number of cylinders that can reduce the load applied to the engine mounting, drive system, etc.

<Structure of the Invention> Therefore, 1. the present invention includes a means for controlling the number of operating cylinders, as shown in FIG. The configuration includes means for performing correction control so as to change the state from the previous state.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. 1st
In FIG. 2 showing an embodiment of the invention, a crank angle sensor 2 attached to a 6-cylinder engine 1 has a crank angle of
A signal a for every degree and a signal s for every 1 degree are output to a control unit 3 composed of a microcomputer. The control unit 3 outputs the ignition signal C to the ignition coil 4 at a predetermined ignition timing based on the signals a and b, and also outputs the switching signal d of the number of operating cylinders to the switching actuator 5 according to the operating state. Here, in order to determine whether to switch the number of operating cylinders, nine signals and other signals are input to the control unit 3, but they will be omitted here. In addition, the switching actuator 5
stops the operation of the exhaust and intake valves of the cylinders that are switched between operating and inactive.

The driving is performed by closing shutters provided on the intake and exhaust pipes, and the switching method does not matter. still,
In a fuel-injected engine, it goes without saying that fuel supply to the idle cylinders is stopped.

Next, the switching control of the ignition timing when the number of operating cylinders is changed by the control unit 3 will be discussed.

FIG. 3(A) shows a time chart when switching from reduced cylinder operation (number of operating cylinders is 3) to full cylinder operation. When the switching operation condition is detected, the switching signal is sent to the switching actuator 5. At the same time, an ignition signal whose ignition timing is retarded from the state before switching is output to the ignition coil 4. As a result, the maximum pressure inside the cylinder can be lowered and the torque generated per cylinder can be lowered, so that a stepwise sudden increase in the torque of the entire engine can be suppressed and the shock to the vehicle body can be alleviated. This reduces discomfort for passengers, reduces the load on the engine mounting and drive system, and improves durability. In addition, there is a lot of residual gas in the cylinder immediately after it is switched from shutdown to operation, and the cylinder wall is cold, making it easy to misfire, but by retarding the ignition timing, ignition can be prevented. can be ensured. After switching, the ignition timing is gradually advanced, and after torque fluctuations have been sufficiently absorbed, the ignition timing is returned to the ignition timing before switching, which is suitable for a steady state.

FIG. 3 (Group) shows a time chart when switching from full-cylinder operation to reduced-cylinder operation; upon detection of the switching condition, a switching signal is output to the switching actuator 5, and at the same time the ignition timing is changed from before switching. The ignition signal with the advance angle corrected is output to the ignition coil 4. By kneading, the torque per cylinder of the three cylinders that continue to operate is increased, and the torque of the entire engine is exposed to a sudden decrease. Also, after switching, the ignition timing can be gradually retarded, and after torque fluctuations have been sufficiently absorbed, the ignition can be returned to the state before switching, which is suitable for a steady state. It will be done.

FIG. 4 shows an example of a time chart of the second embodiment. When a moving cylinder number switching operating condition is detected, ignition timing control is first performed in the cylinder number operation before switching to bring the torque close to the torque immediately after switching, and then switching is performed. In this embodiment, the ignition timing is controlled immediately after switching in the same manner as in the previous embodiment. Regarding the configuration, since the only difference is the ignition timing processing by the arithmetic circuit inside the control unit shown in FIG. 2, the explanation will be given below using FIG. 2 as well.

Figure 4 (A) shows the case where the switch is made from all-cylinder operation to reduced-cylinder operation. When the operating conditions that lead to the switch are detected, the ignition signal is ignited with the ignition timing gradually retarded while maintaining all-cylinder operation. Output to coil 4. This causes the engine torque to gradually decrease. Next, a switching signal is output to the switching actuator 5 to switch to reduced-cylinder operation, and at the same time, an ignition signal is output in which the ignition timing is further advanced than before the switching operation condition was detected. Thereafter, the ignition timing is gradually returned to a value suitable for steady operation, as in the previous embodiment.

In this way, since the engine torque has already decreased before the switching surface, the difference with the engine torque after the switching surface will be smaller, and the torque change will be smaller, so the effect of reducing shock to the vehicle body will be further enhanced. reactor.

FIG. 4(B) shows a case where switching from reduced-cylinder operation to all-cylinder operation is performed. When the switching operation condition is detected, an ignition signal that gradually advances the ignition timing while maintaining reduced-cylinder operation is sent to the ignition coil 4. output, thereby gradually increasing engine torque. Next, a switching signal) is output to the switching actuator 5 to switch to all-cylinder operation, and at the same time, an ignition signal that retards the ignition timing from before the detection of the switching operating conditions is output, and from then on the ignition timing is changed to normal operation. Gradually return to the appropriate value.

In this case as well, since the engine torque increases before the switching surface, the difference with the engine torque after switching is reduced, increasing the effect of reducing shock to the vehicle body, and increasing the reduction of burden on the engine mounting and drive system. .

The sequence control shown in this figure is applied when the accelerator pedal is gradually depressed or when the vehicle speed increases and a switch to all-cylinder operation is required. When torque is required, switching is performed at the same time as the operating conditions are detected, as in the previous embodiment.

FIG. 5 shows a tie chart of a third embodiment of the present invention. That is, in this embodiment, when switching from reduced-cylinder operation to full-cylinder operation, the ignition timing of the cylinder that is always in operation is not changed, and only the ignition timing of the cylinder that is switched from idle to active is controlled for retardation.

That is, as described above, there is a high risk of misfire in the cylinders after the peak of the cylinder that has been switched from rest to operation. Therefore, if the ignition timing of the normally operating cylinder is also retarded to reduce the torque, in the unlikely event that the switching ventilation cylinder misfires, the engine torque after switching will actually decrease more than the engine torque before switching. , operation defects such as engine stalling are more likely to occur.

By changing the ignition timing of cylinders that are always in operation, at least the engine torque before switching can be ensured, and the above-mentioned malfunction can be prevented. In addition, by securing the minimum engine torque in this way, the retard control period for the ignition timing of the cut ventilation pipe can be extended as shown in the figure, so the torque generated by the cut ventilation pipe can be reduced to around 0 and then gradually increased. This makes it possible to make the joint smoother and to further enhance the effect of preventing misfires.

<Effects of the Invention> As explained above, according to the present invention, when the number of operating cylinders is changed, the ignition timing is controlled so as to suppress the change in torque from before the change, thereby reducing shock to the vehicle body. In particular, when switching from reduced-cylinder operation to full-cylinder operation, the load on the engine mounting and drive system can be reduced to improve durability, and the ignition timing can be retarded. It has the following features: it can effectively prevent misfires in the ventilator, and it can improve exhaust characteristics and drivability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a control block diagram showing the first embodiment of the present invention, and FIG. 3 (A)
CB) is a time chart when switching from reduced cylinder operation to reduced cylinder operation in the same embodiment as above, Figure 4fA) is a time chart when switched from reduced cylinder operation to reduced cylinder operation in the above embodiment. Figure (B) is a time chart diagram when switching from all-cylinder operation to reduced-cylinder operation in the second embodiment of the present invention. 5
The figure is a time chart diagram when switching from reduced-cylinder operation to full-cylinder operation in the third embodiment of the present invention. 1... 6-cylinder engine 2... Crank angle sensor 3
...Control unit 4...Ignition coil 5.
...Switching actuator patent applicant Nissan Motor Co., Ltd. agent Patent attorney Fujio Sasashima

Claims (1)

[Claims] In a cylinder number control engine in which the operation of some cylinders is stopped under predetermined operating conditions of a multi-cylinder engine, at least the operation and deactivation are switched immediately after the number of operating cylinders is switched, and the ignition timing of the cylinder to be switched is changed from immediately before the switch. An engine with a controlled number of cylinders, characterized in that it is provided with an ignition timing correction control means for controlling the number of cylinders.